1. Field of the Invention
The present invention relates in general to bar code reading, including a reading system and a reading method. More specifically, the invention is directed to a pre-processing apparatus and method for use in combining fragmentary bar code read data.
2. Description of the Prior Art
Pen-type readers and stationary readers employing laser light are known as a means for optically reading bar codes. Further, so-called one touch type readers that employ a one-dimensional image sensor (hereinafter referred to as a "line sensor") for improving the operability of scanning cylindrical commodities such as bags having irregular shapes and cans have recently been becoming the mainstream of bar code scanning systems.
When a bar code is scanned with a reader of the type described above, if the angle of inclination of scanning with respect to the bar code is larger than a predetermined angle, a part of the bar code falls out of the field of view of the line sensor, so that only a fragment of the bar code can be read. In such a case, in order to read the entire bar code, the operator must repeat the scanning operation.
In order to minimize the difficulty experienced by the operator when repeatedly conducting the bar code read operation, it is conventional practice to set the height of bar codes so as to be greater than a predetermined level. In the case of stationary readers, a bar code may need to be scanned in a multiplicity of directions (e.g., four directions).
Since bar codes are printed on media such as price tags, labels, etc the size of the media is predetermined and the bar code must be sized to fit the media. A special-purpose printer is needed to print the codes on the media. In the case of stationary readers, it is necessary to scan a bar code in multiplicity of directions at the same time, which complicates both the hardware and software arrangements.